fire tree fi·ret·ree uncommon noun 1. a terrestrial evergreen shrub or small tree of western Australia having brilliant yellow-orange flowers; parasitic on roots of grasses Synonymsflame treefire treeChristmas treeNuytsia floribunda Related words Broader terms parasitic plant Parts Nuytsia WordNet 2.1 (Princeton University). WordNet 2.1 Copyright Princeton University. All rights reserved.